U.S. Pat. Nos. 4,975,751 and 5,091,336, the disclosures of which are incorporated herein by reference, describe high voltage component devices with low series resistance. However the recent proliferation of battery-powered, portable communication electronics has increased the need for low voltage, low on-resistance power MOSFETs for efficient power management. Furthermore, because such devices are frequently used in applications that involve inductive loads, it is desirable that they have high UIS (Unclamped Inductive Switching) capability. This is an extremely high stress process, during which the amount of avalanche energy absorbed by the device is expected to be as high as possible without resulting in catastrophic device failure. This capability is generally referred to as the device ruggedness. In addition, some applications such as synchronous rectifiers require that the body diode of a power MOSFET have a low reverse recovery charge.
Unfortunately, there is a conflict among device breakdown rating, on-resistance, improved UIS capability, and desirable body diode characteristics. There is a need for improved MOS devices that exhibit an optimum combination of these characteristics, a need that is met by the present invention.